Method of preparing gammaacetopropanol



Patented Aug. 14, 1945 2382,0711 METHOD or PREPARINGIGAMMAQ Iacn'rornomnon 1 Lucas P. Kyr-ides, Webster Grovespand Ferdinand B-Zlenty, St. Louis, Mo., assignorsteMonsantos 7 Chemical Company, St.Louis,. Mo.,. a.corpora.-.

tion of Delaware No Drawing.

Application September 8, 1944', Serial'No. 553',290

20 Claims. (o1. zsossi) This invention relates to-the preparation. of

keto alcohols and lactones and particularly 'td-a method ofpreparing:gamma-acetopropanol and gamma-valerolactone fromI,4-pentanediol- The dehydrogenation ot glycerol by heat. treatment inthe presence? of copper chromite. as a catalyst results in the formationof? hydroxy-propanone (acetol). Likewise, the dehydrogenation of1,3-butylene glycol by heat treatment in the presence of basic coppercarbonate resultsin the formation of acetoethanoh Consequently thedehydrogenation of Lgi-p'entanediol. by heattreatment in the presence ofcopper chromite would. be

expected by analogy to form gamma -acetopropanol. We havediscovered;however,.that t1' 1i's\proo ess results. in the formation ofgamma-valerolac tone with only traces of gammafacetopropanol Moreover,various promoters the alkali'ne type,

such as sodium hydroxide and sodium carbonate. and other promoters, suchas decolorizingchanyield of gamma-valerolactone. v v

The object of the present invention is to procoal and alundum merelyserve to increase the,

vide a novel process for, the preparation; or,

gamma-acetopropanol and gamma-.valerolacltone from 1,4-pentanediol. j

Other objects will become apparent-from the following specification andexamples.

The method 01' the present inven tiong, gener ally stated, comprises.mixing Lg-pentanediol, with small quantities, for'example fllflflmto 0.1

mole percent, based on the pentan'ediol, of an organic acid, such aslauric, sebaci'c, stearic, -ca.-,.

proic, 2-ethy1 hexoic, phenyl'acetic j and acetic acids, and heating themixtureifor ashort period or time, for example from 5 to 15" minutes, ata temperature below 100 Cl and preferably. under.

reduced pressure. Themixture is thenco oledlj for example.toapproximately 50 C., and" a copper chromite catalyst js. added. Thereaction mixture is then heated to initiate and maintain the. dehydrognation; reaction; and. the crudesreaction. products. are simultaneouslydistilled; from the reaction: mixture. distilled: reaction products are.then slowly redistiil-ldt; inzsuchma' manner that. the temperament: the:condensing;

vapors. doesnot exceed looltorl ofi? CL: aris tillate. consists 0t twolayerazwhich identified;

as a' lower water layer' and an"upper layer of2-methyl-4,5'-dihydrofuran; I The two layers are allowedto standtogether at room "temperattu'e with occasional agitation until ahomogeneous solution is obtained? By'the additionala-small" quantity ofan acid, for examp ww 1 cc; of ,45 normal. hydrochloric, sulfurieoracetic acid, 'to the receiver prior to or duringthe slowdistillati'on,the recombination orthe water thev 2-methyl-4,5-'dihydrofuram to: termgamma-- acetopropansoltakes place substantially asisoon asv the twocomponents aredisiilledinto the receiver.

It is desirable: to add the acid: before "a largeivoltune or distillateis formed; since otherwisernthe recombination may be accompanied byvmrem.

The resultingisolution is then distilled under-re duced pressure. Thedistillateis gamma-aceto-- propanol. I The highboilingresidue-tremthere: distillation of the distilled reactionprodliicts is subsequently distilled to recover gamma-yal erolactone.The remaining 1 residue may be further distilled 'torecover residualunreacted' l -i -pene tanedi'ol. i H I Theoperation of-adding the: smallportionoil acid-t0 the IA-pehtanedMI and short-heiit treab" ment priorto the addition-cf the catalysthave been found to beldesirable in theproductioir'of consistently satisfactory yields of gamma-aceta propanolfrom '1,4-"pentanediol-. The alternatives, namely the additionof thecatalyst before" the addition of the .acidQor simultaneously-there withhave beenfound-*to resultf frequently in somewhat decreased I yields" ofgarmna-:a,ceto ;n" o-- panol and in some instances. only traces ofgamma-acetopropanoltare formed by these alternative. procedures. Theshort pre-heat treatmentalso has-the effectot removineair from the.reaction mixture and thereby. stabilizing the uni. formity of contact ofthe catalyst. yield of" the. desired! product has been found to be morenearly uniform with this practice; l r

y In the preparationof ganmia acetopropzmolby the method: of thepresent'invention, thestill in which the'dehydrog'enation is conducted;maybe re-charged' as many' asinv'e' times" or more afiter each previousyieldoi gamma-acetoprop'a'nol' and gamma-valerolactone isdistilled over:In this manner, the catalyst may be used repeatedly without thenecessity of starting with a fresh batch of catalyst. The catalyst maygenerally be employed for successive batches in this manner until theyield of gamma-acetopropanol on successive operations decreases to anuneconomical level.

In the slow redistillation of the crude mixture recovered from thecatalytic reaction, the previgorous evolution of hydrogen occurred, andthe temperature of the reaction mixture dropped to about 190 C. Thereaction products were slowly distilled over, and the heating wasinterrupted when only a small amount of material remained in thereaction flask. The residue remaining in the flask was allowed to coolbelow 50 C. Then another charge of 52 g. of 1,4-pentanediol wasintroduced into the flask, and the process was continued as before.After two cycles aso-utlined hereinbefore had been completed, thedistillate was transferred to a still. The products which constitutethe; distillate from the reaction flask were then distilled, thetemperature of the still being allowed to rise grad- -'ually to 205 C.while the column head temperwhich instance a more rapid distillation isef- 1' I fected. Under such conditions, a substantial quantity ofgamma-'valerolactonewill be distilled over and the distillate will be amixture of gamma-valerolactone and gamma-acetopropanol. Moreover, thegamma-acetopropanol will be distilled over without first decomposinginto water and 2-methyl-4,5-dihydrofuran. The slow distillation istherefore preferred.

The copper chromite catalyst used in the proc-.

ature was maintained below 110 C. The resulting distillate consisted oftwo layers, a lower water layer and an upper layer of 2-methyl-.4,5-dihydrofuran. The product was permitted to remain at roomtemperature with occasional shaking until a homogeneous solution wasobtained (about 36 to "'48 hours). Then the prod- ;uct wa placed in seenand distilled under reduce'd pressure. Yield, 27% of gamma-aceto- Ipropanol, calculated on the 1,4-pentanediol consumed. Boiling point, 85to 86 C./l0 mm.

ess' of the present invention may be prepared in; the usualmanner for acatalyst-of this type'for" hydrogenation anddehydrogenation purposes. A

suitable method has been found to be that described by CalingaertandiEdgar in the Journal The high boiling'residue'remaining after thedistillation" of gamma-'acet'opropanol from the"- mixture ofreaction-products was distilled under reduced pressure, yielding 44 g.of gammavalerolactone, boiling point,84 'to 88" C./ 13.5 mm.,

of Industrial and EngineeringChemistry, Vol. 26,

pages 878-.9, 1934.'-Brief1y, this process comprises dissolving 250 g.moles ofcopper sulfate pentahydrate and 125 moles of sodium' di-'chromate dihydrate in 3100 l. of water, slowly adding 28% ammonia untilno furtherprecipitation occurs inthemother liquor, filtering theresulting'slurry, washing the filter cake with water until free fromwater-soluble salts, airdrying the cake and oven drying at 110C.Thedried cake is broken up into friable lumps and mixed with sufficientwater tozformwa coherent; mass when squeezed in .the hand. Themass isthen passed through a IZ-mesh 'screen'to' form;

granules which are then roasted at 320 to .340 C;-- 5 until the materialiSflllStIOLl-S black in color and appearance, with, a faint brownishcast.v Thematerial is then pulverized and screened through a. 200-meshscreen; The'resulting material may then be used as thecatalyst in theaforedescribed process. Other methods of preparing the copper 1 chromitecatalyst may be employed, thecriterion being the preparation of .acatalyst having-a suitable degree of reactions.

activity for dehydrogenation The following examples will servetoillustrate the process of the present invention. These eX- amples aremerely'illustrative and are not to be construed as limiting the scope ofthe invention.

ceiver. The mixture was stirred and the system was placed under anabsolute pressure of 25 mm.

The mixture was heatedto 90 C. and the resulting solution was cooledunder reduced pressure The system was vented and 3.0 g. of copperchromite were added.-: Then the. distillation receiver was connected toa'bubble-counter and the mixture was heated; At about200 C. a.

and 5.6 g. of unreacted lA-pent'anediol, boiling few minutes underreduced pressure. The mixture was allowed to cool to the containingvessel was vented tofatmospheric pressure,

and 3.0g. of copper catalyst was added. The. reaction mixture was thenheated atabout. 195}? and the dehyd o en n tilled out slowl material was1 products were dis:

in the flaskjthej heating. was

interrupted and the flask withiits' contents. was; permitted to coolbelow 50,? additionalv quantity of 52 g. of lA -pentan diol was.added,to the reaction vesseljandfthe heating was repeated as before'I'l ie crude vproduct[distillate was. if placed in a still, and the'gamr'na-acetopropanol component was distilled out at. atmosphericpressure to aflnalstilltemperatureof205 C. The

distillate was present in'thelform of. two layers,

an aqueous layer anda layerof,2methyl;4,5 dihydrofuram After about 36hours the two layers had coalesced and vacuum distillationi produced ayield of 22.8%,,Of gamma -acetopropanol, calculated on the1,9l-pentahediol consumed. The. residue from the dis'tillationof the'crude 'dis tillate from which the gamma-acetopropanol r hexoic andacetic acids i componentswas removed: was further distilled 1m derreduced pressure to yield 16 g. of gammavalerolactone and 48g.0f.l-,4.-pent-anediol Gamma-acetopropanol and tone were 2 preparedaccording Example I, using lauric, sebacicf capro'ic, 2-ethyl n place ofstearicacid. d in the following table," ts of Examples I and II thecopper chromite cata- The results are tabulate together with the resuland a control in" which g'. of .1.4flbentaidediol and ll35gamma-valerolac i to the method 'of lyst was employed in the absence: oi

an organic acid. I i

ing L4-pentanediol with. a: .smalhportion of. an

organic acid; for-i a short period of time; cimling.v

Pure Yield of -y-'aceto. y-aceto-y: Egg: propanol propanol The yieldofgamma-acetqpropanol inthe foregoing table is based on theILA-pentanedioll consumed. It. willbe observed from. the tablethat theuse of a mineral acid such sulfuric acid in t P 6 5 in pl ce of anorganic. aci fail d to produce any of the desired gamma-acetone: panol,or even gammarvalerolactone Other organic acids in addition tov thoselisted in the foregoing table have been found. suitable forthe process,of the present invention}, The. quantity of. organic acid used in theprocess oi this invention may be varied over a relatively wide. range,

. from the residue remaining after the redistillaa,

for example from 0.001; or evenv less. to 0.1 mole. percent or more.Ultimately a, point, may be reached at which furthen increases of acidwill tend to interfere with the operatipn of thecatalyst. Suitable acidsfor the purpose of the pres.-

ent invention may be selectedirom the class of monocarboxylic acids andpolycarboxylic acids, including'aliphatic acids such; as butyric,succinic, citric and tricarballylic acids and aromatic acids such asphthalic, terephthalic, is'pphthalic and naphthoic' acids and phthali'canhydri'd e.

Example W The method of Example II was repeated with the followingalteration in the procedure. At the point in the process at which thecrude reaction mixture distilled from-the catalyst was redistilledslowly at a temperature below 110 C., the distillate was collected in areceiver containing 1 cc. of normal hydrochloric acid. During thecollection of the distillate, the contents of the receiver were agitatedoccasionally. In each instance after agitation of the receiver, ahomogeneous solution appeared to be formed in the receiver, indicatingthe rapid reaction of 2-methyl-4,5-dihydrofuran and water to reformgammaacetopropanol in the presence of the small portion of acid. Thisoperation thereby eliminated the necessity for a 36-hour standover, aspracticed in the preceding run.

We claim:

1. The method of preparing gamma-acetopropanol and gamma-valerolactonecomprising heating 1,4-pentanediol with a small portion of an organicacid for a short period of time, cooling the mixture, heating the cooledmixture with a copper chromite catalyst, simultaneously recovering acrude mixture of reaction products from the reaction mixture,subsequently recovering a mixture of 2-methyl-4,5-dihydrofuran and waterfrom said reaction products, allowing said mixture to stand untilgamma-acetopropanol is formed in said mixture, recoveringgamma-acetopropanol from said mixture, and subsequently recoveringgamma-valerolactone from the residue of said crude mixture of reactionproducts.

2. The method of preparing gamma-acetopropanol and gamma-valerolactonecomprising heatthe. mixture, heating the-cooled mixture with a copperchromite catalyst, simultaneously distilling ofi a crude mixture ofreaction products frornthe reaction. mixture, subsequently,redistilling; said crude mixturewith a vapor tempera; ture below 110.,C, to recover a mixture of 2-:

methyl- L5 -dihy-drofuran and water, allowing. aid;

mixture to stand until a homogeneous solution is formed, distilling saidmixture under reduced pressure torecover gamma-acetopropanol, and;subsequently recovering gamma-valerolactone tionof the crude mixture.

3.. The method of preparing gammaacetobrov I panol. comprising heating,1, 4. -pentanediolv with.

a small portion of an organic acid for a short period. of time, coolingthe mixture, heating the cooled mixture with .acopper chromite catalyst,

simultaneously distilling ofi a. crude mixture of reactionproductsfromthe, reaction mixture, sub.-

se uentl'y redistilling said crude mixture with a vapor temperaturebelow,110, C., v allowing, the resulting, distillate to stand until ahomogeneous, solutionis formed and recovering gammagaceto propanbl fromsaid solution. f H W .15- T m thod p ep t inggamma acetoprpg panol Icomprising heating simultaneously distilling oil a crude mixture ofreaction products from the reaction mixture, subsequently redistillingsaid crude mixture with a vapor temperature below C., allowing theresulting distillate to stand until a homogeneous solution is formed,and distilling gamma-acetopropanol from said solution under reducedpressure.

5. The method of preparing gamma-acetopropanol comprising heating1,4-pentanediol with a small portion of an organic acid and a copperchromite catalyst, distilling off a crude mixture of reaction productsfrom the reaction'mixture, subsequently redistilling said crude mixturewith a vapor temperature below 110 C., collecting the distillate in thepresence of a small portion of an acid, and distillinggamma-acetopropanol from I said distillate under reduced pressure.

6. In the method of preparing gamma-acetopropanol from 1,4-pentanediol,the steps comprising heating 1,4-pentanediol with a small portion of anorganic acid, cooling the resulting mixture,

and heating the cooled mixture with a copper chromite catalyst.

'7. The method of claim 6 in which the organic' acid is stearic acid.

8. The method of claim 6 in which the organic acid is acetic acid.

9. The method of claim 6 in which the quantity of organic acid is 0.001to 0.1 mole percent.

'1, 4 -pentanediol with. a small portion of an organic acidiforfafshortperiod of time, 'coo1i ng the mixture, heatin g the, cooledmixtu're'with a copper chromite catalyst','

10. The method of claim 6 in which the quantity of'organic acid is 0.005to 0.01 mole percent.

11. The method of preparing gamma-acetopropanol and gamma-valerolactonecomprising heating a mixture of 1,4-pentanediol, a small portion of anorganic acid and a copper chromite catalyst, distilling off a crudemixture of reaction products from the reaction mixture, subsequentlyredistilling said crude mixture with a vapor temperature below the vaportemperature of boiling gamma-valerolactone, collecting the distillate,allowing the mixture to stand until a homogeneous solution is formed,recovering gamma-acetopropanol from said mixture, and subsequentlyrecovering gamma-valerolactone from the residue remaining after theredistillation of the crude mixture 12. The method of preparinggamma-acetopropanol' and gamma-valerolactone comprising heating amixture of 1,4-pentanediol, a small portion of an organic acid and acopper chromite catalyst, distilling off a crude mixture of reactionproducts from the reaction mixture, subsequently redistilling said crudemixture with a vapor temperature below 110 C., collecting the distillatein the presence of a small portion of an acid,

redistilling said distillate under reduced pressure to recovergamma-acetopropanol, and subsequently recovering gamma-valerolactonefrom the residue remaining after the redistillation of the crudemixture.

13. The method of preparing gamma-acetopropanol and gamma-valerolactonecomprising heating a mixture of 1,4-pentanediol, a small portion ofanorganic acid and a copper chromite catalyst, distilling off a crudemixture of reaction products from the reaction mixture, subsequentlyredistilling said crude mixture with a vapor tem' perature below 110 0.,collecting the distillate mixture, adding a small portion of an acidto-said distillateimixture, allowing the mixture to stand until ahomogeneous solution is formed, distilling said mixture under reducedpressure to recover gamma-acetopropanol and subsequently recover- 16.The method of claim 14 in which the'oranic acid is acetic acid.

1'7. The method of claim 14 in which the quantity of 'organicacid is0.001 to 0.1 mole percent.

s. The method of claim 14 in which the quantity of organic acid is 0.005to 0.01 mole percent.

19. The method of preparin gamma-acetopropanol and gamma-valerolactonecomprising heating amixture of 1,4-pentanediol with a small portion ofan organic acid and a copper chromite catalyst, recovering, a crudemixture of reaction products from the reaction mixture, subsequentlyrecovering a mixture of 2-.methyl-4,5-dihydrofuran andwater from saidreaction products, allowing said mixture to stand untilgamma-acetopropanol is formed in said mixture, recoveringgamma-acetopropanol from said mixture, and subsequently recoveringgamma-valerolactone from the residue of saidwcrude mixture of reactionproducts, substantially as described in the specification and examples.V

20. In the method. of preparing a mixture of gamma-acetopropanol andgamma-valerolactone from 1,4-pentanediol, the steps comprising heating amixture of 1,4-pentanediol, a small portion of an organic acid and acopper chromite catalyst and recovering a mixture of gamma-acetopropaneland gamma-valerolactone from the reaction mixture. Y

I LUCAS P. KYRIDES.

FERDINAND B. ZIENTY.

